SNOQUALMIE VALLEY – Three women died early Sunday when falling rocks bigger than cars crushed their Volvo sedan 1 – 1⁄2 miles east of Snoqualmie Pass.

A huge slab of granite slid off the hillside north of Interstate 90 then broke apart, said Bob Cernick, maintenance supervisor for the Washington State Department of Transportation (DOT) at Hyak.

Most of the rock pieces were “bigger than a car and there was a lot of it,” said Eric Brain of the DOT’s Yakima office.

The slide closed the westbound lanes of the freeway for nearly 14 hours.

The three victims, all 28-year-old women, were headed west when their car apparently struck debris and slid to face south before being crushed by falling rock shortly after 1 a.m., State Patrol reports said.

The women were identified by the Washington State Patrol as driver Janet J. Ichikawa of Lynnwood, and passengers Janel A. Lindsey of Bothell, and Heather E. Rider of Castle Rock.

No other cars or people were harmed by the slide, Cernick said.

When he arrived at the scene about 2 a.m., the slide “covered a couple hundred feet of highway all the way across with 20-ton boulders,” and rocks were still falling, Cernick said.

Snow avalanches occur in the area, but such a massive rockslide is “very unusual,” he said. “I’ve been here 25 years and I’ve never seen anything like it.”

Investigators told The Associated Press the slide might have been caused by the rain the area received in recent days.

By noon Sunday, transportation department crews had cleared the freeway lanes, using two loaders each to push the larger boulders into a ditch, Cernick said.

The rocks will be drilled, packed with dynamite and blasted into smaller sizes to be removed from the roadside at a later date, he said.

After transportation department geologists determined that loose rocks above the roadway remained a threat to drivers, crews made their way to the top of the slide area Sunday afternoon. They rappelled down the rock face and used bars to knock the loose rocks off, Cernick said.

I-90 was reopened by 3 p.m. Sunday.

This story originally appeared in the King County Journal.